Control device



Nov. 3, 1936. N. c. scHELLl-:NGER

CONTROL DEVICE Filed March 5, 1934 4 Sheets-SheetI 1 gef.

NOV- 3, 1936. N. c. scHELLENGER 2,059,712

CONTROL DEVICE Filed March 5, 1934 4 Sheets-Sheet 2 NOV- 3 1936 N. c.scHELLENGl-:R 2,059,712

CONTRQL DEVICE Filed March 5, 1934 4 Sheets-Sheet 3 Inventar.- Newzm 6T,Sczeener NGV- 3, 1936. N. c. scHELl-.ENGER '2,059,712

CONTROL DEVICE Filed March 5, 1934 4 Sheets-Sheet 4 Patented Nov. 3,1936 mm.. DEVICE Newton C. Chicago a corporation o! Scllellenge, Eklnxt,Telephone Supply Co.,

` Indiana Ind., asslgnorto Ind.,

Applicaties mnh s, 19:4, sam n. 113,91: 4 canna. (ci. zoo-153i Thisinvention relates to control device: and particularly to a switchadapted to be 'used in combination with another control device such as avariable resistance device.

This switch is particularly adapted to be used in structural andoperative combination with volume or tone control units for radio setsfor switching the power supply of a radio set. The switch meets the veryrigid requirements of the radio trade, due to its small size, long life,relatively high current carrying capacity, nlggedness, the very uniformlow contact resistance that is maintained throughout the life of theswitch, the large number of switching combinations that can be obtained,and its adaptability for use with either A. C. or D. C. power supply bythe interchanging of a single element of the switch. The maintenance ofa very low contact resistance is of great importance especially when alow voltage, high current power supply is used, such as in the case ofmany battery operated radio sets. An increase above normal of only a fewthousandths of an ohm in the contact resistance may render the setinoperative due to the considerable drop in voltage resulting from thisincreased resistance. In the switch of my invention there is arelatively high contact prsure when the switch contacts are engaged anda long wiping movement of one contact over the other during the openingand closing movement, which features serve to keep the contactingsurfaces free from contamination and result in Ithe maintaining of avery low resistance betweenthe contacts.

It is well known that, in a switch carrying alternating current, lessarcing results when the contacts are separated slowly than when they areseparated rapidly. Reference may be made to my copending applicationSerial No. 703,917, filed December 26, 1933, for a detailed discussionof this problem. However, it should be noted that when a direct currentis carried by a switch, it is very essential that the switch contacts beseparated very rapidly in order that the arc will be extinguished in theshortest possible time, otherwise serious burning of the contacts mayresult. Since many diierent soluces oi' power `such as 6 volt directcurrent, 125 volt direct current and 125 volt alternating current, areused for operating radio sets, it is obvious that a single type ofswitch, namely, either a slow break or a fast break switch, cannot beused for all of these applications if the maximum switch life is to beobtained.

In the switch of my invention the requirmxent for alternating currentoperation, namely, a slow break action, wherein the contacts are openedslowly, can be satisied by the use of an actuator or cam that providesonly a small amount of angular lost motion on the control shaft. Thevrequirement of a fast separation of the contacts,- necessary where theswitch is used to control direct current circuits, can also be satisiiedwith switch by substituting a cam having a greater amount of lost motionon the control shaft than the "cam used to produce a slow break action.In either case an audible and tactile signal indicates when the switchis thrown to the oi position. Herefore, where it was desired to obtain aquick break action, it was necessary to use a switch of entirelydifferent design than that used where a slow break action was desired,which requirement resulted in unnecessary expense .and inconvenience tothe user. The switches used in these combinations were of complicatedstructure employing a comparatively large number of parts and they weremounted on the associated control devices in such a manner that it wasimpossible to obtain a thorough electrostatic and electromagneticshielding between the switch and the other control device.

In switches of the prior art which weresuitable for use in combinationwith another control device, the inherent nature of the switch designs`were such that they were not readily adaptable to 'the variousswitching combinations. In mosty cases it was possible to construct theswitch only as a single-pole-sngle-throw or single-pole-double-throwtype and, in a few instances, as a doublepolesinglethrow type.Obviously, a switch having such a range of combinations has but alimited application. In many applications it is desirable to employ asingle switching device of unitary construction to control as many asfour separate circuits simultaneously or in a prede- "termined sequence.

Most of the prior art switches required a considerable force to throwthem to the open circuit position. This resulted in an undesirableincrease in resistance being offered to the rotation of the controlshaft when the shaft was rotated through that portion of its travelwherein it eiected operation of the switch. Thus, the control shaftwould turn easily throughout most of its movement and then suddenly amaterially increased resistance to rotation would be encountered, whichwas usually found to be undesirable.

One of the objects oi the present invention is the provision of asimple, rugged, compact and m. w me .mm m .u m Wm m ..m www... wm.. mm

w mmm m mm .wwwmmmwmmmmmmmwmmm mmmmmm www www www 1m mmmmmmmwmmmmmmmmmmmmmmwmmm NW m mm m mim mmmmwm mmmmmmmmmm mmmmmmm @www mm...MMMMWMTMMEMWMmmm,mmmmmwmdmmmww L? ...m mu M.. al m n w ,m m um?Mmmmmm m? f i? Mm mmm u mm Mm.. ML m m .m m l m m M mMmwmmmgmmggmmwmmmmmmmmmmmmmmmmmmm if m 5:2 m23 n m mmmmmmmmm www Mmmm www@ MmmmMmmm www mm mm m m www mmm mmmmmmmw, ym www www www EN mmm mmmmmwmm mm Mmmm w um mm Mw m m Mum? hmmm mm v ,.m mw mm. mm mmm mmmmm gmx@mmmmmmmmmmm m mmm mm Em Emmmmmm mmmmmm i MM,m www..

m MM mw m mm m M wmmohmmmmmmmmmm.mmmmmdmmmmmmmmmmmmmmmmmwmmmmmmmmMmmm 2Mmmm wmmmmmmmmwmmmmmmm@www mmmwmmmm mmmmwmwmmmmwmwwm theedgesoftheperforatiouliemthisplane,thns a substantially at molmtingsurface is provided. The bearing lbthus constitutedservesbothasa journalbearing for the reduced portion ilb o! the shaft i6andasathrustbearingcooperating with the shoulder adjacent the reducedportion lib. A thrust washer i! interposed betweenthe bearing 'lb andthe shoulder provides a. smooth intermediate thrust bearing and insurespositive electrical connection between the shaft ami the cover.

This bearing 'lb cooperates withthe other bearing Mb to provide tworelatively widely spaced supports. Since the shaft II is engaged by thebushing I4 only along a short length of the shaft I6, the end |6b of theshaft li which enters the other bihing lb can be slightly tilted topermit the shaft i6 to enter thebearing lb ifthe bearings Mb, lb are notin exact alinement; this also prevents binding of the shaft i5 in thebearings Mh, 1b.

Axial displacement of the shaft ii in one direction is limited by thedrive yoke il and members: interposed between it and the flanged headiler of the bushing M and in the other direction by the shoulderadjacent the reduced portion lib bearing against the thrust washer l!which in turn bears against the flat end of the bearing lb.

When the shaft i6 is rotated, the drive yoke il' moves the drive platei2 angularly on the base l to vary the angular position of the presuremember I0, thus the contacter S is moved over the surface of theresistance element t to vary accordingly the length of the resistanceelement Il" between the contacter 5 and end terminals 5, E respectively;thus, the effective resistance between the contactor terminal l5 and theend terminals 5, 6 respectively is varied in accordance with therotational adjustment of the shaft i6. Movement of the movable elementsdriven by the shaft |6 is limitedinbothdirectionsbyastop 'le bentinwardly from the cover member 'l and lying in the path of the end ofthe drive yoke il.

The construction and operation of the variable resistance device aredisclosed more in detail and The switch 2 comprises a base or housingmem-V ber 2| of molded insulating material having a recess 2|a in whichis disposed a pair of contact members 22, 23 formed ofspringtemperphosphorbronze or other suitable resilient conductivematerial. One contact member 22 has a notched end portion 22a extendingthrough a notch 2|b in awallofthehousing2Lakmgstraightportim- 22bextending fromthenotchedendporrtlontos. return bend 22e whichis seatedinan arcuate seat 2 lc in the housing. and a movable end portion 22dwhichbears against eitberthewallof abocs 2id formed in the housing 2|,or against the end of the other contact member 23, depending uponwhether the switch 2 is in open circuit or closed circuit position. Thecontact member 22 k clamped between the housing 2| and the insulatingplate 20 (see Fig. 8) when the switch 2 is secured in positionvon thecover 1, and is thus securely positioned in the housing 2| without theuse of auxiliary fastening members such as screws, rivets or the like,otberthanthemembersnccesnrytosecurethe switch! tothe variable resistancedevice I.

The wall of the housing is cut back at a portion lle adjacent the longstraight portion 22h of the contact member 22 which extends between thenotched end portion 22a and the return bend 22e, to permit this longstraight portion 22h of the contact member 22 to bow when the contactmembers 22, 23 are in engagement, thus providing a greater effectivelength of the contact member 22 than would exist if this section of thespring were supported to restrain its bend- M The Aother contact memberor selector spring 23 is held in placein the switch casing 2| in amanner very similar to that just described. A notched end portion 23aextends through a notch 2U in the side wall of the housing 2i, anormally straight portion 23h extends to return bend or fold 23o whichis wedged in a narrow recess 2|g in the housing 2|, and another bend 23dis engaged and supported by a hom 21h in the housing 2| so that a slightpressure is applied to the portion 23h intermediate the fold 23e and thenotched end portion 23a which tends to bow this portion somewhat; thehousing 2| has a cut back portion 2li to permit this bowing action. Thefree end of the selector spring 2t has formed between the end 23f andthe supported bend portion 23d, an offset portion 23e having slopedsides and adapted to engage a notch Zia formed in from the periphery ofan actuating member or cam 24. The end of the selector spring 23 isturned back slightly to provide a fiat tip 23f so that a smooth surfaceof considerable extent is presented to the other contact member 22 whencontact is made; thus a minimum amount of wear will occur and thecontact resistance will be maintained uniformly low.

The operating member or cam 2l is mounted on a atted portion |6c of theoperating shaft i6 of the variable resistance device i, which shaft I6extends through the cover 'l and insulating plate 2l into the interiorof the'switch housing 2l.

A limited amount of angular rotation of the a relatively flat' cam 2lrelative to the shaft I6 is permitted hole 2lb of double fan shape, thatis, wide at both r ends and narrow in the middle and having its sidesanguiarly to meet arcuate ends. The hole 2lb is formed with its greatestdimensicm (as measured in the plane of the face of the cam)approximately equal to the greatest dimension of the iiatted portion licof the shaft with the width of its narrowed center section approximateiyequal to the width of the flatted portion lic of the shaft Ii. Theswitch housing 2| is recessed to provide a small clearance aroundtheperipheryofthe cam 24sothatitwillbe shifted only a small amount fromits operating position when the shaft Ii is not in engagement therewith.The shoulder formed at the base of the ilatted section lic holds the cam24 close to an annular boss or support 2|i formed in the switch housing2| so that axial movement of the essemployedinthetwopiececamhowever-.the

usuallyprei'erable as will ap- Sinceeachmemberotthetwopiececamisonlyhalissthickasthecamitseli',eachmem bereanpunchedtmmasheetotilbermore reumymdwim smoother edsesuimtne onexer,single member ofthe one piece cam.

Byiormingthecamll o!twomembers.itis

lary attraction and will lubricate the surface of the selector spring 23where it is in contact with the cam due to capillary attractionmaintaining a illm o! oil between these moving surfaces. Ii desired, athin felt pad (notshown) may be interposedbetweenthemembersofthecamutoassist in retaining the lubricant.

The contact member 22 is formed in the shape shown in Plz. 6. Thenotched end portion 22a is perforated and adapted to project from thehousing 2| (as shown in Fig. 8) to constitute a terminal for the switch2 and the principal prtion is reduced in width so that it will not bindagainst the housing 2| or insulating plate 2l when clamped in positionbut free movemmt oi thlsportionotthecontectmemberlwillbepetmitted. Themovable end portion 22d is enlasted slightly to provide a wide contactsurfseebutnotenoughtocauseblndlng. Theremrn bend :ze is foi-med with aconsiderably greater angle than tbc angle into which the contact member22 is bent when assembled in the houdng 2|.

The contact member 2! is assembled in the switch housing 2| by springingthe straight portims 2lb, 22d closer together. engaging the notch of thenotched end 22a with notch lib in the housing 2|. pressing the contactmember 22 into thehousinllluntilthecontactmembernisiullyseatedinthehousingll,andreleasinthe' portions 22h, 22d so that thecontact member 22 Thcseleetorspringisnormallytormedssshowninll'lmbyaplmchpressoperationh'l'heendaoitheselectorspringlikewiseisformed withaperiorationand projectsfromthe housing 2| to constitute a terminal. The principalportionlsalsoreducedinwidthtopreventrubbing on thehousim 2| orontheplate Il.

bysmsehmsomuonpnwtmmemuynr Thecamalsomsybei'ormedoi,

thecamu. Thespngpressureoftheoontsctzlmemberwheninthlspositiontorcestheeam 2l out oi' its normal position sothat it bears againstthewallofthehousingll.

'Iheswltchlisplacedinpositionontheeovermemberlotthevsriableresistanoedevicelwith the insulating plate 2linterposed betweenthe switchlsndthecovermembertandpositlonlng lugsllkextendlngtrom the switchhouslnzli through corresponding periorations(not shown) intheinsulstingplatezlandthecovermemberll'Itomnintsinthesemembersinproperanzulsr relation.Thelwitehlisthenpermsnentlysecuredinplscebyrivetsllthatextendthroulhholesintheswitchhousingllandthroughoorrespondingholesinthelnsulatingplatellandcover-'LV Thisciampsthecontactmembenll,ottheswitchlbetweentheendwalloftheswitch housing 2l andthe insulntlngplete 2l.

Theendottheattenedportion Ileot the shaft Il istapered so that en -thecover member Iwiththeswitehlmmntedthereonisamanbled with the remainderot the variable resistance devieeLtheshaitllwilleentertlmecamllintheswitchhousingllsndslipintoplaoe. TheextentofthetnperclritheenlloftheslmftIllisslwaysslightlyinexcessofthedistancethecamllcanbeforeedoilcenterbytheseleetor springlwhentheshaftliisnotinplusothat no dimculty is encountered with sssembb'.Itwillthusbeobservedthstlhaveprovidede switch with a very eileetiveelectrostatic and electromagnetic shield between the currmtcarryingmembersottheswitchsndthecurrentcarryin! membersofthevarisbleresistancedevice. Theshsftllextendingthroughthebearinglbinthecoverclosesthisopeningsndtherivetsll closetheotheropeningswimtheexoeptiond thoseengagedbythepositioningbossesllk. I!deslred,rivetscanbeemployedasthesolemeamofposltloningtheswitchcasingllonthecoverl.andthebossesllksndcooperatingholesdispensed with.Whenthisisdoneallopeninxsinthecover'lbetweentheswitchlandthevariableresistancedevlceiareillledwithmetallicmemberlineontactwiththecoverl.Iheooverlwillnormsllyn beirroundedthmushtheshnttIltowhiehitiselectrically connected by the metal washer IIsctingasathrustheu'ingbetweentheshoulderonthcdialtltsndthebearinxlbinwhichthe shattiioperates.Theshnttllilloumslledinll and therefore electrically connected to thebushing I4 which will normally be in contact with a lgrounded metalpanel when the control device is in operation. In the event that agrounded metal panel is not used, a supplemental grounding connectionwill be necessary to effectively ground the shielding arrangement.

The switch 2 is operated in the usual manner by rotation of the shaft I6controlling the variable resistance device] and normally the switch 2 isarranged to be operated during the movement of the movable contactor 9of the variable resistance device I through that portion of the movementwherein the contacter 9 is not in contact with effective portion of theresistance element 4. The operation of the switch 2 will be clear.' ifreference is made to the diagrammatic illustrations of Figs. 9 to 11inclusive.

The switch 2 is thrown into its open circuit position by rotating theshaft I6 in the direction indicated by the arrow in Fig. 9 until theleading edge of notch 24a moves into engagement with the sloped side ofthe offset portion 23e whereupon the selector spring 23 exerts arotational force on the cam 24 due to the relationship of the slopes ofthe two cooperating surfaces to each other and the pressure exerted bythe contact member 23. This rotational force results in the cam 24suddenly increasing its speed of rotation and taking up the angularclearance between the cam 24 and the flattened portion IBc of the shaft,and the offset portion 23e of the contact member 23 partially enters thenotch 24a in the cam 24.

This movement of the cam 24 takes place substantially independently ofthe flattened portion IBc so that the walls of the central opening 24hin the cam 24 through which the flattened portion I6c extends, engagethe flattened portion I6c and prevent further movement of the cam 24independently of the shaft I6. When the cam 24 is in this position thecontact members 22, 23 are still in contact as shown in Fig. 10.Movement of the cam 24 from the position shown in Fig. 9 to that shownin Fig. 10 occurs with such speed that a plainly audible click is heardwhen the cam 24 is stopped by the flattened portion I 6c, thusindicating that the operation of opening the switch 2 has been started.In addition to this audible signal, a tactile signal is given by thesudden jerk imparted tol the shaft I6 by the movement of the cam 24.Movement of the cam 24 and selector spring 23 from the position shown inFig. 10 to that shown in Fig. 11 is controlled by the shaft I6 so thatthe contact members 22, 23 are separated at a relatively low speed, asis desirable for switching an alternating current circuit, and come torest with the offset portion 23e of the selector spring seated in thenotch 24a in the cam 24. When this point in the movement of the switchmembers is reached, the rotational force exerted on the cam 24 by thecontact members 22, 23 will cease, thus giving a tactile indication thatthe switch 2 has been opened.

Since the selector spring 23 exerts a rotational force on the cam 24during the time the inclined surface of the projection 23e bears uponthe edge of the notch 24a in the cam 24, the cam 24, unless restrainedby the shaft I6, will not remain in any position wherein its edgeengages the inclined surface of the projection 23e, but will be rotatedby the selector spring 23 to permit the projection 23e to seat itself inthe notch 24a in the cam 24, thus permitting separation of the contactmembers. Thus, if the shaft I6 is normally rotated to a position whereinthe inclined surface of the projection 23e engages the edge of the cam24, and the shaft is then released, the cam 24 will be' rotated to theopen" position and will carry the shaft I6 with it.

'This action is employed to prevent the shaft I3 from being left in aposition such that the contact member 22 and the selector spring 23 areclose enough together to permit intermittent arcing or sputtering which,of course, is highly destructive to the contact member 22 and selectorspring 23. The contact member 22 and the selector spring 23 are soformed and arranged that they are separated sufficiently when in thefull open position to prevent an arc being maintained or reestablished.If the shaft Ii is left in a position wherein the contact member 22 andthe selector spring 23 are intermediate the full open" and full closedposition, the selector spring 23 will bear upon 'the edge of the notch24a to rotate the cam 24 to full open position in the manner abovedescribed.

The contact members 22, 23 are so shaped and arranged that the tip 23fof the selector spring 23 breaks contact with the other contact member22 at a point which lies intermediate the movable end 22d of the contactmember 22 and the point at which this member is engaged by the tip 23!when the members 22, 23 are in fully closed position. Thus, burning ofthe contact member 22 will take place at this intermediate point andhence even if the contact member 22 is weakened due to the burning,there will be no diminution in the pressure which it will exert againstthe selector spring 23 when the members are in closed position.

With the switch 2 in the open circuit position as shown in Fig. 11 theselector spring 23 has its offset portion 23e nested in the notch 24a inthe cam 24 so that the tip 23f is at its greatest distance from theother contact member 22. The switch 2 is thrown to its closed circuitposition by turning the shaft I 6 of the variable resistance device Iwhich effects rotation of the cam 24. As the cam 24 rotates oppositelyto the arrow, the offset portion 23e of the selector spring will belifted out of the notch 24a in the cam 24 and the tip 23j will engagethe contact member 22 near the end of the movable portion 22d to closethe circuit and, as the selector spring 23 is moved further by rotationof the cam 24, the tip 23j will wipe along the portion 22d and reach itsfinal position simultaneously with movement of the offset portion 23e ofthe selector spring 23 onto the circular peripheral portion of the cam24.

'Ihe sudden reduction in the rotational force necessary to rotate theshaft I 6 that occurs as the offset portion 23e of contact member 23moves onto the circular portion of the cam24 gives a positive tactileindication that the switch 2 has been closed. Further rotation of thecam 24, which will occur as the variable resistance device l is operatedwill not change the relative position of the contact members 22, 23.

When it is desired to use the switch in a direct current circuit theangular lost motion between lthe shaft and the cam is increasedsuiliciently to permit the contact members to separate in the normalcycle of switch operation without being under control of the shaft. Theswitch modiiled for this use is shown diagrammatically in differentpositions, in Figs. 12 to 14. 'I'his form of switch is identical withthe previously described form except as to the design of the cam.

In the switch shown in Figs. 12 to 14, the cam |24 has a perforationI24b formed with wider tion |2Ie of the contact member |22 starts toride down into the notch |2041 of the cam |20 and rotate the cam |20faster than it ismoved by the shaft H0. When the cam |24 passes throughthe position shown in Fig. 13 the contact members |22, |20 have juststarted to separate andthecam|20ismovingrapidlsnhilvingtaklen`upmostoftheangulariostmotionwiththe shaft ||0 imder the rotativeinfluence of the seiectorpring |22. The cam |20 and selector spring |20continue to travel unrestrained by the shaftI|0untiltheyreachapositionintermediate thatshown in Fig. 13 and the nnalopen circuit position shown in Fig. 14. The cam |20 strikes against theflattened portion of theshaft |10 just prior to the time the switchmembers attain the position shown in Fig. 14 to thus produce a clickindicatingthattheoperationhasbeencompleted.Thecircuitisclosedinexactlythesame mannerasdescribedabovewiththecontactmembers |22. |20 brought into t with eachotherataspeeddeterminedbytherateof rotationoftheshaft ||0.

It is, of course. obvious that the switch canbethrownintotheclosedcircuit positionand then into the open circuitposition by rotating the cam in one direction for 360' or more and thateither operation can be performed byrotatingthecamineitherdirection,providing,of course, that the locationof the rotational stop means of the variable resistance device willpermit such rotation.

chattering or jumpy operation is prevented when the cam 20 is rotated ina counter-clochwisedlrection (asseen in Fig. 5),fromthe on to the offposition. by the portion 20h bearing againstthebend20dwithsufiicientpressureto preventtbebendndmovingawayfromtheboss 2lbimder the forces encountered in use. Without this reinforcing pressurethe frictionai component between the selector spring 23 and the cam 20tends to move the bend 22d away from the boss 2|h until sumcientpressure is built up to overcome the frictional force at which instanttheselectorspringwilljmnpbacktoitsoriginal position with the bend 22dagainst the boss 2in. This bracing arrangement also prevents damage tothe selector spring 22 when the switch2isclosedbyrotatingthecami2l,fromthe "oil" position to the on positionin a. counterclockwise direction. that is; by an operation reverse tothe normal mode of operation. which reverse operation tends to push thebend 22d away from the supporting boss 2|h.

It is often desirable to provide for switching several separate circuitssimmtaneoly. 'rms is readilv accomplished by the present invention bymounting the required number of switch units in tandem as shown in Pig.15. Each switch imit 202 is from the adjacent switch unit 202 by a plateof insulation 226 that extends beyond the terminals 222 and preventsaccidental short circuiting in connecting-external circuits, and theswitch 202 nearest the variable resistance device is insulated from thecover 201 by an interposed insulating plate 220. Each switch 202 ismaintained in angular alinement with the adjacent switch 202 byproiectionsor lugs 22|k extending from the open face of the housings 22|and engaging 22|m in the end walls of the adjacent housings 22| andnotches 220m-and 220m in the plates 220 and 220. .Rivets 220 that sextend through perforations 22|L in all of the housings andcorresponding perforations 2201... 220L in the insulating plat- 220, 220and perforations in the cover 201 of the associated variable resistancedevice, serve to secure the l0 switch housings 22| and variableresistance device 20| all together and assist the'lugs 22H: and recesses22|m in preventing angular displacement of` the switch housings 22|.'Ihe operating shaft :Il ls nsttened and extends tnroushall 1s switchhousings 22| except the one most remote from the variable resistancedevice 20| and engages all of the'switch cams 220. The cams 220 are heldin axial position by annular collars molded in the housings 22| similarto the eol- 20 lar 2li ln the housing 2| and by spacingwashers 221 ofinsulatingmaterialdisposedonthcahaft 2|0 between the insulating plates220, 220 and thecam22ltoservethepurposeoftheshoulder ontheshaftI0inthesing1eswitch arrangement. $6 nach switch unit in operates 1n ummultiple stmctureinthesamemannerasdescribedforlationshipofthenotchesinthecamstotheilat 00 ontheshaftcanbedii'ferentinswitches so that they will operate sired sequence. In such cases it ableto widenthenotchesinsome sothatsomeoftheswitcheswillremain open circuitposition throlmh a greater shaft movement than in the other switches.

I claim:

l. An electric switch comprising a base having a recess therein, acontact member disposed on O said base, a second and resilient contactmember having a portion formed with a return bend, said portion beingheld between the side walls of said recess by the inherentw force of thecontact member, said ent contact member el having alsoafreeend on.andasecondhand provided between said return bend and said free end portionand bearing against thefportion of the contact member-on the other sideof the return bend to prevent translatory movement of l0 said free endportion in one direction, a side wall of said recess engaging saidsecond bend to prevent translatory movement of said free end portion inanother direction, and means for bending the free end portion ofsaid'second contact Il member into engagement lwith said ilrst contactmember.

2. An electric switch comprising a plurality of contact elements, atleast one of said contact Aclements beingresilient, means slidablyengagen able with a resilient contact element for controlling themovement thereof into and out ofengagement with its cooperating contactele ment, said means including two axially adjacent cam membersperipherally engaging said reu silient contact element, a shaft mountingsaid cam members and means disposed between said cam members forlubricating the engageable surfaces of said cam and said resilientcontact element.

3. A switch comprising a plurality lof contact elements at least one ofwhich is movable into engagement with another of said contact eiements,means mounting said contact elements in cooperative relation, means forcontrolling the 'n engagement and disengagement of sad.contact elementsincluding a cam element formed of a plurality of brous insulating discsengageable with said movable contact element, removable and nsertablemeans for rotating said cam element in engagement with said movablecontact element, and a suitable lubricant between said -discs.

4. An electric switch comprising a plurality of l0 contact elements, atleast one of which is recontrolling the engagement and disengagement ofsaid contact elements including a cam engaging and operating saidresilient element, and a. shaft for actuating the cam, said camconsisting of a plurality of superposed cam layers engaging said movablecontact element with their edge portions, there being lubricant disposedbetween the adjoining faces of saidlayers, whereby to lubricate theengageable surfaces of the cam and movable contact element.

NEWTON C. SCHELLENGER.

